Air filter



FIG. 1 is a perspective view of an air filter showing my new design;

FIG. 2 is a top plan view thereof;

FIG. 3 is a bottom plan view thereof;

FIG. 4 is a left side elevational thereof;

FIG. 5 is a right side elevational view thereof;

FIG. 6 is a front elevational view thereof;

FIG. 7 is a rear elevational view thereof; and,

FIG. 8 is a cross-sectional view thereof taken along the length of the filter and shown at a larger scale.

The broken line showing of parts of the drawings is included for the purpose of illustrating use and environment and forms no part of the claimed design. 

The ornamental design for a air filter, as shown and described. 